You don't activate your magic or superpower without an announcement. After all, randomly bursting into flames at a dinner party would be rather rude of you, if you were the Human Torch.

So you put together a ritual that triggers things, complete with a Catch Phrase. You shout "Flame On!" and the other dinner guests—or anyway, the audience—knows things are about to get flame-y.

In short, you (the writer) invoke your character's power to suspend disbelief long enough to do something way out of the norm. It can be an incantation or Power Words. More often than not, though, it's just the Rule of Cool in action, rather than an actual incantation.

Except for the Chinese Girl. She uses "Kai Men!" (The same phrase, but in Chinese.)

Mirai from Moldiver doesn't need to shout "Metamorforce!" when she triggers the Mol Unit, she just does it because she thinks it's cool.

"[Insert colour] Pearl Voice!" in the Mermaid Melody Pichi Pichi Pitch manga is either this or the Magical Girls' hero identities' naming format; it's not entirely clear which, but if it is a transformation phrase, it's an Invocation, because they certainly don't say it all the time. In the anime, though, it's clearly By the Power of Greyskull instead.

Emiya Shiro from Fate/stay night tends to say "Trace, on" (or off) whenever he uses his Projection spell. It doesn't really seem to do anything aside from making himself concentrate on the spell, considering that his future self only says it once in the entire game (naturally, to confirm that he was the future version of Shiro).

Justified in the game. Most magic in the setting is done by simply channeling Mana through your magic circuits (presumably in the correct manner), but since this is hardly a natural human action, mages tend to make up verbal spells that they associate with specific magic circuit usages. What the words actually are is irrelevant, since it's simply a kind of self-hypnosis. Of course, since this is the Nasuverse, we always get exceptions, in this case Medea who uses Divine Language where apparently the sounds themselves create their own magic circuits and one person from Kara no Kyoukai: who talks to the world and convinces it to change.

Yu-Gi-Oh!!: Every duel is officially begun by the duelists shouting "It's time to duel!" or "Let's duel!" Each turn also tends to end with "Your move" or "Your move, (opponent name)." Though the real-life manual indicates that this is simply good manners. The Japanese Invocation is simply "Duel!"

The Yu-Gi-Oh! GX English tended to use "Duel!", except for Jaden's "Get your game on!" and the occasional "Let's duel!"

Pretty much any long running Humongous Mecha series with Calling Your Attacks will present it but invariably they will be shown doing the attack at some point without calling it.

While Lelouch Lamperouge does actually need to speak for his geass to do anything, he'll occasionally add "Lelouch vi Britannia commands you..." to let you know that he means business.

Slayers is a mixed bag. On one hand, the protagonist Lina doesn't strictly need to use the words of her incantations beacuse she's a pro. On the other hand, they do work better when she does. If pressed for time she'll just say the first line to get in the mood and skip to the spell name.

The Shinigami in Bleach can use their Kido spells without any incantation (by simply calling the spell's level number and name), but the resulting effect is usually far weaker than it would be if they had had the time to recite it (some of them are really long—see below). However, it takes a somewhat skilled Kido user to be able to use it without the incantation and not have it blow up in their faces.

Since their use of Kido is almost strictly for combat (save for some healing and shielding spells, and even those are sometimes used in combat), they tend to either recite the incantation beforehand if at all possible, or simply use it without the incantation. This, of course, means that when a skilled Kido user (especially a captain-level one) recites the incantation for a spell, the HSQ of the target goes to through the roof (unless, of course, that target is Sousuke Aizen, in which case he'll just stare blankly and say something to the effect of "Since when were you under the impressionthat your pathetic spells can hurt me?").

While the incantations are usually very word salad-y, they are also pretty cool:

"Ye lord! Mask of flesh and bone, flutter of wings, ye who bears the name of Man! Truth and temperance, upon this sinless wall of dreams unleash but slightly the wrath of your claws. Hado, number 33: Sōkatsui!"

"Limit of the thousands hands, respectful hands, unable to touch the darkness. Shooting hands unable to reflect the blue sky. The road that basks in light, the wind that ignited the embers, time that gathers when both are together, there is no need to be hesitant, obey my orders. Light bullets, eight bodies, nine items, book of heaven, diseased treasure, great wheel, grey fortress tower. Aim far away, scatter brightly and cleanly when fired. Hado, number 91: Senjū Kōten Taihō!"

Shinigami who have not reached bankai must also release their shikai with a command, followed by the name of the zanpakuto.

The Wonder Twins' "Wonder Twin Powers Activate!" was originally revealed as being this in the Superfriends tie-in comic. They didn't say it because they needed to, but rather just because they thought it was cool.

In Dune the Harkonnen Mentat recites a mantra after drinking "sapho" juice as part of a ritual to heighten his mental powers. This does not feature in the book and was an invention of the director/actor.

Similar to the Fate/stay night example above, djinn in the Children of the Lamp book series use a particular "magic word" as an aid in focusing on their magic, but the word itself is arbitrary. The only rule is that the word be somewhat long and complex, but this is just to make sure that the djinni in question doesn't accidentally use magic in the course of daily conversation. Thus we get everything from real words like "SESQUIPEDALIAN" and "ZYGOBRANCHIATE" to the meaningless but familar "QWERTYUIOP" to the truly nonsensical "FABULONGOSHOOMARVELISHLYWONDERPIPICAL".

Played with in the Dresden Files. Ritual, Calling Your Attacks, and even Focii are all just to help the wizard visualize their spells. Only a very few spells (usually heavy-duty summoning or massive rituals) actually require more than mental focus at all levels of talent and power. However, they help, so wizards do them. But then, since a wizard's power is tied to their beliefs, its possible that this trope (and all the other listed stuff) becomes necessary. Note, though, that invocation also has another feature, insulating the mind against the magic - which is why wizards all choose dramatic, old languages that they don't speak, because that gives them a bit of distance from what they're saying.

All the Objects from The Lost Room have a special invocation: turn the Key, Comb the hair, tap someone with the Bus Ticket...

Amanda, the human-raised Q in Star Trek: The Next Generation, makes little gestures when using her powers, as does the suicidal Q in Star Trek: Voyager. No other Q does this. Unless you think Trelane was a Q. Though those who hold to this theory often also decide Trelane wastheQ. Although, Q did tend to snap his fingers when using his powers, on-and-off. Presumably, all are doing it for dramatic effect, except Amanda, raised as a human.

Incidentally, the idea that Trelane was a (but not the) Q is usually considered Fanon, as it was central to one of the best respected Star Trek novels, Q-Squared. Trek novels, however, are never actually canon.

The shows are barely canon themselves, from one to the next; what do you want from an E.U.?

The "looking over the glasses" motion was also used by the Lois and Clark incarnation of Superman, when he used x-ray or heat vision. Which makes sense for heat vision (cos otherwise he'd melt his glasses) but why can't you x-ray through glass?

Refraction?

Power Rangers falls into this a lot. Particularly on occasions when rangers actually show that they can morph without calling out some codeword, but rather just quietly pushing the button on their morpher. Plus they often have to call out the name of the weapon they want to use, even if it was sitting right there in their holster!

Whenever Rodney McKay snaps his fingers repeatedly, he is about to enter full-genius mode (possibly due to his Chance-Of-Impending-Doom-O-Meter is about to go Off the Scale). How it's connected with his brain activity is unknown, but it lets the viewer know he is up to something.

With the second Rider (who was the first to do it) the phrase opened the cover of the Transformation Trinket so the wind-powered transformation would begin. (Kamen Rider #1 didn't have the cover, and he said nothing initially. However, when he returns after a long absence, he takes up his successor's habit.) But yeah... all the others seem to be doing it for just dramatic effect, and furthermore, are not instructed to say it by anyone when they first get their powers.)

"How do I get this thing started? Oh man...Dear evil, messed up, demon powers. Of darkness. Please transport me off this awesome corpse pile. I am but a visitor in this strange world, which some would call hellish, but I have to admit is kinda badass."

"Oh, mighty sun. Burn the creatures of the night from this land while I enjoy coffee and bacon!"

Colette's Mystic Arte, Holy Judgement, from Tales of Symphonia. The invocation for Holy Song, one of her Angel Artes with the effect of buffing the team, is usually: "Thy faithful servant asketh for thy blessing. Honor us with the splendor of thy song." However, when doing the Mystic Arte, Colette slips up and intones: "Thy faithful servant asketh for thy blessing. Honor us with the special... uh... oops! I messed up!" Instead of the spell failing, however, Colette's divine clumsiness results in the spell setting off Holy Song and Judgement at the same time, both significantly increased in power.

Cortez in Time Splitters: Future Perfect with the incredibly cheesy "Time to split!" line before travelling through time. Most of the rest of the cast notice the cheesiness and occasionally comment on it, particularly Super Spy Harry Tipper.

Parodied in Eat Lead: The Return of Matt Hazard, where Matt says his catchphrase "It's hazard time!" before doing anything. Everyone makes fun of him for it.

Nu: From beyond the realm of souls and birth I call upon the ur-sword to bring ruin on my enemies. Perish!Tsubaki: White feathers for innocence, black feathers for darkest sin. We are the messengers and hammers of God, come to deliver righteous justice! Let sinners be punished! Let justice be done!Hazama: By the darkness of a thousand souls, in the name of Susanooh. I command you awaken! Nox Nyctores Ouroboros!Mu: The seven celestial gods! The world created by the hands of the gods. Everything is false! Everything is a lie! The final days have come! Now, let everything be destroyed!

In Advance Wars, whenever a CO activates his Power/Super Power, he will say something cool before.

In Skies of Arcadia, every magic spell is invoked with "Moons, give me strength!" Its the same for every spell, regardless of what it does. Likely just something to get them focused.

Eternal Sonata has this in spades. Every special attack needs to be invoked, and if the power gauge is more full (resulting in a more powerful attack and a longer more dramatic pause), a longer invocation is said. Most aren't even coherently audible... =/

An important part in the worldbuilding of Yggdra Union and Blaze Union, where the most common form of attack magic—Tactics Cards—are representations of magical contracts that have been given form by a rare and very powerful type of magic called the Power of Words. Given that the Power of Words has essentially founded the current system and is based in speech and writing, a player who knows about the worldbuilding will easily be able to spot Nessiah as a critically important character by the fact that he wields a spellbook, not a staff. This character is actually the founder of the Tactics Cards system himself; he put himself through hell to master the Power of Words, too.

Valkyrie Profile has some truly epic statements being made when it comes to the great magics; the sequel was a little lacking in that regard. Invoking the Harmoniums of Asgard to summon Ancient Lightnings is pretty awesome. The physical warriors also get some pretty impressive ones with their Purify Weird Soul moves. It's probably not necessary to announce "My soul burns; my power has awakened!" right before transforming into a giant dragon to blast foes to oblivion; it certainly is memorable, though. These were similarly toned down for Valkyrie Profile: Silmeria.

In the Strong Bad Email "transformation", Strong Bad always prefaces his transformations with "Shape of... (something)!" Then, the transformation would be accompanied by a "DWAYNE!!" sound effect in Strong Bad's own voice.

Used by Generator in the Whateley Universe to activate her faux 'devises'. They're actually powered by her 'autonomous telekinetic constructs', which is to say basically disembodied copies of herself who generally already know what they're supposed to do, but by shouting 'activation commands' she deliberately creates the illusion of being just another mutant high-tech geek.

Danny Phantom's "Going ghost!" He's transformed just as many times without saying it, most memorably for a stretch of episodes after his new arch enemy mocked it.

American Dragon: Jake Long's "Dragon up!" When partially transforming, he would name whatever part he changed; "Claws of the Dragon" or what have you.

Inverted in Transformers: Cybertron. The Tagalong Kid's Humongous Mecha transforms for the first time without the vocal trope. The regular characters tell him he should shout "Transform!" the next time, as it makes the process much more exciting. (He does.)

Transformers: Beast Wars, on the other hand, made a big show of having the characters shout "Maximize!" or "Terrorize!" along with an elaborate Transformation Sequence...for one season. After that, the Invocation was pretty much dropped without comment from anyone.

On the other hand, after Blackarachnia's transformation to a Transmetal II and accompanying conversion to the Maximal side, she makes a show of accompanying her first transformation in her new body with Blackarachnia, Maximize!", informing the viewer that her transformation did, in fact, remove her Predacon programming.

The episode that introduced the Fusors Quickstrike and Silverbolt has Megatron hacking into their CPUs and altering their transformation codes from "Maximize!" to "Terrorize!" and then uses it as proof that they have always been Predacons and just forgot. Silverbolt, though, doesn't like the word but has no other reason to disbelieve Megatron.

Additionally, since Dinibot keeps doing Face Heel Turns and Heel Face Turns, he "officially" changes his transformation code to the opposite as proof or his new loyalty. Nobody buys it, of course.

She didn't use an actual Catch Phrase, but Storm in the 1990s animated X-Men would often describe the weather pattern she was creating... in Purple Prose, not unlike a witch's spell. See the page quote above.

Jérémie on Code Lyoko can transfer his teammates to Lyoko without saying "Transfer... Scanner... Virtualization" and jump back in time without saying "Return to the past now!"

Indeed, during a couple of Season 1 episodes, the RTTP kicks in without any help from Jérémie, purely from narrative habit. In one of the two, he was unconscious at the time and nowhere near the building, at that.

The Fanon explanation for these is that Aelita can launch herself the Return to the Past from inside the Tower.

Staring a match: In Battle Brawlers, the players would use a special card and yell, "Field Open!", stopping time outside the field. Closing the field would happen automatically, or if the players used the same cards and said, "Field Close!', as seen in a few episodes. New Vestroia has "Gauntlet, Power Strike!", with the same time-stopping effect for those not in the match. It differed in that, unlike Battle Brawlers, the battle didn't take place in a pocket dimension, even on Earth, leading to a lot of post-battle destroyed buildings.

Using a Bakugan: While throwing their Bakugan onto the field, players would always yell, "Bakugan Brawl! [Name of Bakugan] Stand!". New Vestroia added throwing a Bakugan Trap into the air, with a similar command: "Bakugan Trap! [Name of Trap]!" May possibly be just Rule of Cool, as the invocations sometimes varied.

Gate and Ability Cards: "Gate Card, Set!" and "Gate Card Open: [Name of Card!", though the latter may actually be required to activate the card. New Vestroia's Gate Cards seem to always be called [Attribute] Reactor, but Battle Brawlers had a lot more variety. Similarly, "Ability Activate! [Card Name]!" triggered a special ability. New Vestroia added "Double Ability", "Triple Ability", and "Fusion Ability" to the game, making for some wildly improbable but highly cool combos. Battle Brawlers had the Ability Cards held and activated similar to Field Cards, but New Vestroia had the brawler put the card(s) into their Gauntlet to activate them.

↑Technically, it's not an actual Invocation, but Domon says it every time he uses the attack so it might as well be.